In the semiconductor processes for forming films, the growth procedure, the anneal procedure, the diffusion procedure, and the baking procedure, etc., all need to perform a thermal treatment under a thermal environment. Therefore, the application of the thermal treatment step in the semiconductor processes is very common. Presently, the thermal treatment step can be typically performed in a batch type furnace or a single-wafer type rapid heater.
Referring to FIG. 1, FIG. 1 illustrates a schematic diagram of a conventional furnace. In a furnace 100, an O-ring (not shown) located on a manifold 110 will deteriorate under high temperature. Hence, a pipeline under the O-ring in the manifold 110 is used to allow process cooling water to flow through so as to lower the temperature of the O-ring. The process cooling water is injected into the pipeline in the manifold 110 from a bellows 102, and after the process cooling water flows through the entire pipeline, the process cooling water is drained out from a bellows 104. High-temperature resistant metal is typically adopted as the material forming the bellows 102 and the bellows 104 for furnace process.
The knurl portions of the bellows 102 and the bellows 104 are thinner for bending capability, so that the knurl portions are weakest in the entire bellows suture. When there is corrosion gas, such as chlorine etc., or other rusting gas in the process environment, the knurl portions of the bellows structure will be corroded, thus causing the cracks of the bellows. The cracks of the bellows will leak the process cooling water to contaminate process. Because there are many metal impurities and particles in the process cooling water, these metal impurities and particles will fall on the wafer 108 with the leaking of the process cooling water. After a thermal treatment step, the process cooling water evaporates, and the metal impurities and particles in the process cooling water adhere on the wafer 108, thus greatly lowering process yield and seriously degrading the quality of devices.